Acoustic wave apparatus

Abstract

An acoustic wave apparatus includes a piezoelectric substrate including a piezoelectric layer including first and second principal surfaces opposed to each other, first and second IDT electrodes directly or indirectly on the first principal surface, and first and second dielectric films on at least one of the first and second principal surfaces. A portion of the piezoelectric substrate including the first IDT electrode, the first IDT electrode, and the first dielectric film define a first acoustic wave resonator. A portion of the piezoelectric substrate including the second IDT electrode, the second IDT electrode, and the second dielectric film define a second acoustic wave resonator. Each of the first and second dielectric films includes Li and Ta or Li and Nb. At least one of a piezoelectricity, a direction of polarization, or a crystal structure is different between the first and second dielectric films.

What is claimed is: 
     
         1 . An acoustic wave apparatus comprising:
 a piezoelectric substrate including a piezoelectric layer including a first principal surface and a second principal surface opposed to each other;   a first IDT electrode and a second IDT electrode directly or indirectly on the first principal surface of the piezoelectric layer; and   a first dielectric film and a second dielectric film on at least one of the first principal surface or the second principal surface of the piezoelectric layer; wherein   a portion of the piezoelectric substrate including the first IDT electrode, the first IDT electrode, and the first dielectric film define a first acoustic wave resonator;   a portion of the piezoelectric substrate including the second IDT electrode, the second IDT electrode, and the second dielectric film define a second acoustic wave resonator;   each of the first dielectric film and the second dielectric film includes Li and Ta or includes Li and Nb; and   at least one of a piezoelectricity, a direction of polarization, or a crystal structure is different between the first dielectric film and the second dielectric film.   
     
     
         2 . The acoustic wave apparatus according to  claim 1 , wherein the first dielectric film includes a LiTaO x  film or a LiNbO x  film, where x is a freely-selected positive number. 
     
     
         3 . The acoustic wave apparatus according to  claim 1 , wherein the second dielectric film includes a LiTaO y  film or a LiNbO y  film, where y is a freely-selected positive number. 
     
     
         4 . The acoustic wave apparatus according to  claim 1 , wherein
 at least one of the first dielectric film or the second dielectric film includes Li and Nb; and   the piezoelectric layer includes Li and Nb.   
     
     
         5 . The acoustic wave apparatus according to  claim 1 , wherein
 at least one of the first dielectric film or the second dielectric film includes Li and Ta; and   the piezoelectric layer includes Li and Ta.   
     
     
         6 . The acoustic wave apparatus according to  claim 1 , wherein
 the first dielectric film is on the first principal surface of the piezoelectric layer; and   the first IDT electrode is indirectly on the first principal surface with the first dielectric film interposed between the first IDT electrode and the first principal surface.   
     
     
         7 . The acoustic wave apparatus according to  claim 6 , wherein
 the second dielectric film is on the first principal surface of the piezoelectric layer; and   the second IDT electrode is indirectly on the first principal surface with the second dielectric film interposed between the second IDT electrode and the first principal surface.   
     
     
         8 . The acoustic wave apparatus according to  claim 1 , wherein
 the first dielectric film is on the second principal surface of the piezoelectric layer; and   the first IDT electrode and the first dielectric film are opposed to each other with the piezoelectric layer interposed between the first IDT electrode and the first dielectric film.   
     
     
         9 . The acoustic wave apparatus according to  claim 8 , wherein
 the second dielectric film is on the second principal surface of the piezoelectric layer; and   the second IDT electrode and the second dielectric film are opposed to each other with the piezoelectric layer interposed between the second IDT electrode and the second dielectric film.   
     
     
         10 . The acoustic wave apparatus according to  claim 8 , wherein
 the piezoelectric substrate includes a support substrate; and   the first dielectric film is between the support substrate and the piezoelectric layer.   
     
     
         11 . The acoustic wave apparatus according to  claim 1 , wherein thicknesses of the first dielectric film and the second dielectric film are different from each other. 
     
     
         12 . The acoustic wave apparatus according to  claim 1 , wherein
 the acoustic wave apparatus is a single filter including a plurality of acoustic wave resonators; and   the plurality of acoustic wave resonators include the first acoustic wave resonator and the second acoustic wave resonator.   
     
     
         13 . The acoustic wave apparatus according to  claim 1 , wherein
 the acoustic wave apparatus is a multiplexer including a plurality of filters; and   the first acoustic wave resonator and the second acoustic wave resonator are included in filters different from each other of the plurality of filters.   
     
     
         14 . The acoustic wave apparatus according to  claim 1 , wherein the acoustic wave apparatus is configured to have a pass band in a range from about 2496 MHz to about 2690 MHz. 
     
     
         15 . The acoustic wave apparatus according to  claim 1 , wherein the piezoelectric layer includes a piezoelectric single crystal layer including Li and Nb or Li and Ta. 
     
     
         16 . The acoustic wave apparatus according to  claim 1 , wherein each of the first and second IDT electrodes includes electrode fingers including side surfaces inclined with respect to a direction normal to the first principal surface of the piezoelectric layer. 
     
     
         17 . The acoustic wave apparatus according to  claim 1 , wherein each of the first and second IDT electrodes includes electrode fingers including side surfaces parallel or substantially parallel to a direction normal to the first principal surface of the piezoelectric layer. 
     
     
         18 . The acoustic wave apparatus according to  claim 12 , wherein the plurality of acoustic wave resonators include a plurality of series arm resonators and a plurality of parallel arm resonators. 
     
     
         19 . The acoustic wave apparatus according to  claim 1 , wherein each of the first and second IDT electrodes includes a Ti layer, an Al layer, and a Ti layer laminated in this order. 
     
     
         20 . The acoustic wave apparatus according to  claim 10 , wherein the support substrate includes Si.